Adipose tissue is located under the skin layer. Thus, energy applied to the skin surface to degrade adipose tissue must pass through the skin layer to reach the adipose tissue without damaging the skin.
Various devices have been used for the treatment of adipose tissue. One popular method of fat treatment is liposuction. This is an invasive technique involving mechanical disruption of the tissue fat with subsequent suction of the resulting debris out of the body. The main disadvantage of this method is its invasive character.
U.S. Pat. No. 5,143,063 describes a method for treating adipose tissue based on thermal destruction of fat by exposing adipose tissue to focused microwave or ultrasound waves. The intensity and the focusing of the energy is determined so as to selectively destroy fat cells without damaging the skin or deep tissues.
U.S. patent application Ser. No. 2004/0039312 filed February 2003 discloses the application of high intensity focused ultrasound (HIFU) for destruction of adipose tissue. U.S. Pat. No. 6,607,498 discloses HIFU pulsed so as to produce cavitation, which selectively destroys fat cells.
U.S. Pat. No. 5,725,482 discloses superposition of ultrasound waves from two or more sources to create a wave having high intensity localized at the adipose tissue to be treated.
High intensity focused ultrasound (HIFU), whether the mechanism is cavitation, thermal treatment or another form of treatment, has a basic disadvantage, due to the small focal diameter, which is typically only a few millimeters. This focusing is necessary for preventing damage to the skin layer. However, it makes it very difficult to treat large areas of soft tissue, as the applicator head has to be moved over the skin surface in very small steps. Because of the pliable character of the adipose tissue, movement of the applicator over the skin surface displaces the adipose tissue to another position, thereby creating a risk of over treating some tissue volumes and under treating other tissue volumes.